The present invention relates to a process for the production of concentrated solutions of hydroxylammonium nitrate (HAN) and hydroxylammonium perchlorate (HAP). More particularly, hydroxylammonium sulfate is added to a slurry of either barium nitrate or barium perchlorate at a rate which is slower than the rate of solution of the barium salt. This permits dissolved barium salt to react with the dissolving hydroxylammonium sulfate thereby obtaining solutions of either hydroxylammonium nitrate or hydroxylammonium perchlorate.
Concentrated HAN and HAP solutions are traditionally made by vacuum evaporation of water from dilute HAN or HAP solutions. The dilute solutions are made by stoichiometric reaction of a saturated barium nitrate or barium perchlorate solution with hydroxylammonium sulfate (HAS). The maximum concentration of the HAN or HAP solutions that can be initially obtained from a saturated, boiling water solution of barium salt is about 20%. However, since the product stability of the HAN and HAP can be affected by the temperature of boiling water, the reaction is actually conducted at lower temperatures and yields about a 15% solution.
The dilute HAN and HAP solutions are removed from the by-product barium sulfate precipitate by decantation after settling. The precipitate is so fine that normal filtration and washing are difficult and several washes are required to minimize product losses. The concentration at the start of vacuum evaporation is normally about 10% HAN or HAP and solutions of varying concentrations may ultimately be prepared. Because of the heat sensitivity of both the HAN and of the HAP, concentrating the product is a long, slow, dangerous process.
Previous attempts to obtain more concentrated solutions from the original reaction have repeatedly shown, that unless the barium salt was dissolved before mixing, the results were erratic and considerable barium salt remained unreacted.